Pressure regulators for controlling the pressure of oil within an internal combustion engine system are well known in the art. In typical applications, a pressure regulator is positioned between an oil supply line and an oil bypass line. Generally, the pressure regulator is designed to control the oil pressure in the engine system by allowing at least some of the oil in the supply line to be released into the oil bypass line when the pressure of the oil in the supply line reaches a prescribed threshold. In this manner, oil pressure regulators maintain the pressure of the oil in the system below a predetermined upper limit.
Certain pressure regulators include a plunger that is movable within a chamber to prevent and allow the release of oil from the oil supply line into the oil bypass line. In conventional regulators of this type, the plunger is biased into a seated position against the chamber by a compression spring. The plunger commonly includes through-holes that are open to both the oil supply and bypass lines to allow oil to flow therethrough when the plunger is moved into an open position away from the seated position. The plunger moves away from the seated position toward the open position as the pressure applied to the plunger by the oil in the oil supply line exceeds the biasing force of the spring. As the pressure of the oil increases, the increasing biasing force of the spring is overcome and the plunger is moved toward the open position until a threshold pressure, corresponding with the plunger being in the open position, is reached and oil is allowed to flow into the bypass line. Accordingly, the characteristics of the compression spring are selected according to the desired threshold pressure of the system. As oil is bypassed from the supply line to the bypass line, the overall pressure of the oil in the system decreases and the plunger moves away from the open position toward the seated position. In this manner, the oil regulator controls the oil pressure in the system in a passive manner through the give-and-take interaction between the compression spring and the oil pressure of the system via the plunger.
Conventional regulators are configured with biasing elements that force the plunger into a seated position against an open end of the chamber when there is no pressure within the system or the pressure within the system is low. In other words, when the oil pressure within the system is not enough to overcome the biasing force of the spring (e.g., during idling or when the engine is off), a pre-compression of the spring applies a biasing force against the plunger to urge the plunger into contact with the chamber.